1. Field of the Invention
The invention concerns a method for counteracting heeling of a sea-going vessel due to a movement of first masses on the vessel, by means of movement of second masses thereon, which movements create respective static moments about the vessel's centre of gravity.
2. Description Background Art
From the prior art as illustrated in FIG. 1, it is known that semi-submersible platform 100 can be employed as support structure for a rocket 101 which is to be launched, e.g., in order to place a satellite in an orbit around the earth. In this connection some of the preparation work for the rocket 101 is performed while it is located lying in a hangar, i.e. while the rocket's longitudinal axis extends horizontally. The rocket with the mounted satellite is then transported out of the hangar to a launching site on the platform 100 where the rocket 101 is raised to a standing position which is illustrated in FIG. 1, in which its longitudinal axis extends vertically, whereupon fuel 102, i.e. first masses, is pumped from tanks 103 on board the platform 100 to tanks 104 on board the rocket 101 by means of a pump 105, i.e. a first device for movement of the first masses. The pump 105 may be connected with a control device through an electrical conduit 106. The rocket 101 is then launched.
In a rocket of this type, its height is relatively great in relation to the diameter of its rear end section whereby it rests on the launch site, and in the event of substantial heeling there is a risk that it may overturn. However, minor heeling must also be avoided, since the hull of the rocket may be overloaded. For example, the heeling should not exceed 0.5 degrees. There is a special need to monitor the heeling when rocket fuel is being pumped on board the rocket from tanks in the platform, since large quantities of fuel are involved.
For controlling the platform's draught, the use is known of a ballast device comprising tanks from which sea water can be filled or emptied. For compensation of a heeling of the platform, it is similarly known that by means of the same ballast device sea water can be pumped from one tank on board the platform to another. This filling and emptying can be performed by means of suitable pumps, valves, etc. However, the angle of heeling is established before, e.g., any heeling compensation takes place.
If a standing rocket as described above is located on a platform of this type, and the rocket is being filled with fuel, an inadmissably high degree of heeling and reduction of the rocket's stability may therefore occur before any compensation of the heeling can take place, nor can the possibility be overlooked that the rocket's stability may be affected by additional forces as a result of wind and waves.